NASA recently announced the development of the Space Launch System -- an advanced heavy-lift launch vehicle that will provide an entirely new national capability for human exploration beyond Earth's orbit. The Space Launch System will give the nation a safe, affordable and sustainable means of reaching beyond our current limits and opening up new discoveries from the unique vantage point of space.

The Space Launch System, or SLS, will be designed to carry NASA's Orion Multi-Purpose Crew Vehicle, as well as important cargo, equipment and science experiments to Earth's orbit and destinations beyond. Additionally, the SLS will serve as a back up for commercial and international partner transportation services to the International Space Station.

The SLS will incorporate technological investments from the Space Shuttle Program and the Constellation Program in order to take advantage of proven hardware and cutting-edge tooling and manufacturing technology that will significantly reduce development and operations costs. It will consist of Core and Upper Stages with common avionics. It will use a liquid hydrogen and liquid oxygen propulsion system, which will include the RS-25D engine from the Space Shuttle Program for the Core Stage and the J-2X engine for the Upper Stage. SLS also will use dual solid rocket boosters for the initial development flights, while follow-on boosters will be obtained through competition based on performance and interface requirements. The SLS will have an initial lift capacity of 70 metric tons, or more than 154,000 pounds. The lift capacity will be evolvable to 130 metric tons, or more than 286,000 pounds. The first developmental flight is targeted for the end of 2017.

The specific architecture was selected after careful analysis of the combination of technologies that would most effectively meet the SLS capability requirements. The architecture also utilizes an evolvable development approach, which allows NASA to address high-cost development activities early on in the program and take advantage of higher buying power before inflation erodes the available funding of a fixed budget. This architecture also enables NASA to leverage existing capabilities and lower development costs by using liquid hydrogen and liquid oxygen for both the Core and Upper Stages. Additionally, this architecture provides a modular launch vehicle that can be configured for specific mission needs using a variation of common elements. NASA may not need to lift 130 metric tons for each mission and the flexibility of this modular architecture allows the agency to use different configurations by using Core Stage engines, Upper Stage, and booster combinations to achieve the most efficient launch vehicle for the desired mission.

The SLS vehicle procurements will be structured to meet the Agency's requirement for an affordable and evolvable vehicle within a schedule that supports various mission requirements. Procurements will include utilization of existing assets to expedite development, as well as further development of technologies and future competitions for advanced systems and key technology areas specific to SLS evolved vehicle needs. Detailed synopses will be issued in the near future for the individual procurements as required by regulation.

Initial planning is for the following:

- Boosters - utilization of the five segment Ares First Stage Boosters under the existing contract for the initial flights, the first of which is targeted for the end of 2017.

- Advanced Boosters - to be utilized for missions beyond the initial flights -The Agency will not specify solutions (i.e. liquid or solid propulsion may be proposed), but will instead solicit solutions to meet performance and interface requirements. -A risk reduction solicitation will be issued later this calendar year to improve the competitiveness of competing propulsion technologies and business cases before work begins on the actual Design, Development, Test and Evaluation (DDT&E) of the final booster configuration. -DDT&E will be solicited in the 2013-2014 timeframe after results are received from the risk reduction effort.

More details will be forthcoming in the near future to include presentations at the SLS Industry Day to be conducted on September 29, 2011, at the Davidson Center, in Huntsville, AL. Registration information can be found at http://prod.nais.nasa.gov/cgi-bin/eps/synopsis.cgi?acqid=148572 . Questions and comments may be submitted to Earl Pendley, telephone number 256-544-2949, or via email at george.e.pendley@nasa.gov.